The term “transitional life form” is relative, and is intended to reference the gaps in the fossil record. For example, the phrase is useful in recognizing transitionary organisms between a fish and reptile, reptile and bird, reptile and mammal, etc. Obviously, there are such genetically connecting life forms that exist between phyla. In a certain sense, with the exception of the very first original single-cell organism, all living creatures are a “transitional life form” between their parent (or life form of higher taxa further distant in ancestry) and their offspring. All life forms are genetically embedded (nested) into the hierarchical tree of life somewhere. There’s no exception. If there were just one specimen that were an exception then Darwin’s theory would crumble. Even without natural selection or the evolutionary process, nested hierarchy in and of itself proves common descent. Evolution explains common descent This does not negate creationism or ID. Neither sides “wins” by a default due to a failed hypothesis of an opposing theory. This might be how a political debate is decided, but not how scientific conclusions are derived.
Dr. Duane T. Gish, Ph.D. (Biochemistry, Univ. of California, Berkeley) wrote the following in his book, Evolution – The Fossils Say No! published by Creation-Life Publishers, San Diego, California 1973:
“On the basis of the evolution model, we would predict that the most ancient strata in which fossils are found would contain the most primitive forms of life capable of leaving a fossil record. As successively younger strata were searched, we would expect to see he gradual transition of these relatively simple forms of life into more and more complex forms of life. As living forms diverged into the millions of species which have existed in the past and which exist today, we would expect to find a slow and gradual transition of one form into another.
“We would predict that new basic types would not appear suddenly in the fossil record possessing all of the characteristics that are used to define its kind. The earliest forms in each group would be expected to possess in incipient form some of the characteristics which are used to define that group while retaining characteristics used to define the ancestral group.” (Gish, page 31)
TRANSITIONAL LIFE FORM ARGUMENT:
This is an extremely important point here because this is the core essence of the issue. One the one hand, one could easily claim that in a certain sense all living creatures are examples of transitional life forms. According to cladistics and phylogeny, all life forms can be classified by taxonomists and situated in their proper place on the evolutionary tree of life, which is called “twin nested hierarchy.” Twin nested hierarchy refers to the fact that any life form is obviously a transitional step between their parent and their offspring, and as such, will fit genetically in place with it’s family lineage. The theory of common descent explains that this lineage goes all the way back to a single common ancestor, and this is verified by cladistics.
On the other hand, this might all well be fine, but this is NOT what ID proponents and creationists are referring to when they object to common descent based upon the transitional life form argument. The objection is that there are no transitional life forms that show the intermediary steps of evolutionary development of biochemical structures. Regardless of the biochemical system, whether it is bones and skeletal structure, organs, appendages, or whatever biochemical feature there might be, all of these characteristics are fully formed. There is never any demonstration provided where an biochemical system is in transition from one function to developing a new function. This is the transitional life form argument. The “form” reference here in this context is not a whole organism, the “form” requested here is a biochemical structure of an organism that is showing an intermediate stage in evolutionary development from one function to a new function.
The response to this objection by proponents for common descent is that the notion that there should be organisms which demonstrate intermediary features that are not fully formed is preposterous. The response is that every fossil specimen represents a fully evolved species, and that to request an organism not showing only partial development is a misconception. Darwinists contend that the transitional life form argument is a misrepresentation of evolutionary theory, and that it is a misconception to require an organism to partially look like an ancestor and partially like a descendant. Darwinists further state that evolution predicts that all organisms should appear as modified versions of preexisting forms, and that it is flawed logic to look for specimens in the fossil record that reveal an amalgamation of ancestral features with with modern representations of the group. Those who promote evolutionary theory use the absurd “crocoduck” to illustrate this point.
As I mentioned already, this is a very important point to be made. No one takes the crododuck seriously because it is obviously ludicrous. The request for organism to be presented showing intermediary developmental stages of partially one function and partially another function is not an unreasonable request. Of the hundreds of millions of species there are, truly if evolutionary hypothesis of common descent was a plausible theory, then of those billions of organisms alive today and in the fossil record, there should be some examples showing intermediary steps transitioning from one function to the development of a new function. This is the request. This is why ID proponents and creationists relentlessly never cease to claim there are “no transitional life forms.” This is what what we are specifically referencing.
Now, let’s take a look at some of the examples offered by Darwinists in response that they claim are transitional life forms.
TRANSITION FROM AMPHIBIANS TO FROGS and SALAMANDERS:
It is established in cladistics and taxonomy that frogs and salamanders share a common ancestor. Paleontologists observe that frogs and salamanders have more in common with their relatives, the caelcilians, than frogs and salamanders have to each other. This has led to two hypotheses:
1. One prediction is that frogs and salamanders share a very closely immediate common ancestor.
2. The second prediction is that there will also be found a common ancestor of both frogs/salamanders and caelcilians. This unknown life form is also the ancestor of caelcilians. Since this unknown hypothetical organism has never been discovered, the hypothesis remains unresolved. That is the way the situation is to the present day.
Enter the specimen, Gerobatrachus [http://3.bp.blogspot.com/_m6sVhskT_Fs/SDRuF479kMI/AAAAAAAAB7A/nPwNkvS1cyA/s400/8308_web.jpg]. Gerobatrachus confirms the first hypothesis. Gerobatrachus looks like a frog, and is very frog-like. Gerobatrachus is often called the “frogamander” [http://en.wikipedia.org/wiki/Gerobatrachus]. It’s fossil does appear to be longer than a modern frog, which would link it more to a salamander [http://scienceblogs.com/pharyngula/2008/05/25/gerobatrachus.jpg].
However, Gerobatrachus has some interesting characteristics that defy evolution. The specimen fossil reveals Gerobatrachus was about 5 inches long, and it is a tough little frog. It has just about every feature there is of a modern frog, but Gerobatrachus also has a full set of teeth. Modern day toothless frogs are forced to swallow whole everything they catch. Gerobatrachus is stronger, bigger, tougher, badder, and fitter than any modern frog or salamander I have ever observed. Gerobatrachus could kick modern frog’s butt. The fact that modern frogs do not have teeth, and are inferior in their fitness to the Gerobatrachus tells me that what we have demonstrated here is REVERSE EVOLUTION, where instead of gaining complexity, some features were lost. I do not refute that Gerobatrachus is the common ancestor of frogs and salamanders, but in each instance of evolution, complexity was lost, not gained.
Is Gerobatrachus a compelling transitional life form? No, Gerobatrachus is a transitional life form in the sense that its phylogeny would fit in its proper place in a clade that links salamanders and frogs. That is evidence for common descent, but common descent is not the issue in this discussion topic. This discussion topic is specifically attempting to find and identify an organism that demonstrates a transitional stage of intermediate evolutionary development. If frogs (no teeth) descended from Gerobatrachus (full set of teeth), then where is a traditional life form between the two that shows half-developed teeth? Gerobatrachus is fully formed, complete, with all biochemical features functioning perfectly and fully operational.
Turtles have a shell. Instead of teeth, turtles have beaks! Turtles actually demonstrate convergent evolution, which is an argument for design because the beak of a turtle is the same design of beaks that birds have. But, that’s all beside the point. We are looking for a transitional life form that demonstrates an intermediary step of evolutionary development.
A study of turtle embryology reveals an interesting insight to turtle development because in the embryo the shell forms first before other features. This leads to several hypotheses that predict there will be an ancestral fossil of a turtle discovered somewhere that will display evidence that the shell evolved first before other turtle characteristics.
Enter Odontochelys [http://scienceblogs.com/pharyngula/2008/11/26/odontochelys.jpeg]. Just like Gerobatrachus was very much a frog, Odontochelys is 100% turtle. Remember how Gerobatrachus had teeth, but modern frogs don’t? Well, same with Odontochelys. Odontochelys has teeth, but no beak [http://en.wikipedia.org/wiki/Odontochelys].
What is compelling that Darwinists would like you to note is that Odontochelys has a complete lower shell, but no upper shell. In fact, Darwinist try to put a spin on this by saying the upper shell is “incomplete.” No, there is no upper shell, period. Broad ribs and backbone are not a “shell.” Darwinists who promote this specimen as a transitional life form are hoping that you would be naive enough to think that broad ribs and backbone count as a “shell.” Sorry, they don’t.
I am pleased to see that Odontochelys satisfied the evolutionary theory hypothesis that would look for a variation of the shell in a primitive form of a turtle. Here, we see microevolution at work, variations and adaptations taking place. But, our hunt for a transitional life form that shows an intermediary stage of development continues.
Odontochelys fails to delivery as a transitional life form that reveals intermediary development stages. (1) First of all, the part of the shell that is actually a shell on transitional life form is FULLY DEVELOPED and functioning as a shell. The upper area of the body has NO SHELL, just ribs and backbone functioning the way those bones function, and not functioning as a shell. A compelling transitional life form would have showed us a shell that was still developing, but still not fully functional as a shell. (2) Odontochelys has a FULLY DEVELOPED TEETH, and no beak. A compelling transitional life form would have demonstrated at least what would appear to be a beak-like mouth, or teeth beginning to recede and take the shape of a beak. But, all we have are organisms that either have a fully develope set of teeth, or a fully functioning beak, with absolutely not trace of a developmental stage showing transition from teeth to a beak.
Darwinists claim that snakes descended from an ancestor that had limbs. They point to evidence that indicates snakes have what they believe are vestigial hind limbs. There are at least three (3) fossils of snakes that appear to have hind legs. These are:
In each of these instances, the so-called hind legs, often called “rudimentary legs” on some snakes are acknowledged as having a function during reproduction, as claspers during copulation. Those are not legs. This is not a transitional life form showing an intermediary stage of development, and neither are these examples of vestigial organs either.
Not only is there no transitional life form provided here showing any intermediary step between an ancestor and a descendant, but we don’t even have the ancestor to begin with. There are no snakes with legs. There is nothing with legs that evolved into a snake in the first place. It is meaningless to show a transitional life form when there is no ancestor offered to compare the transitional life form to.
Basically, what we need to satisfy the objection or transitional life form argument, is you need an organism A, which is the ancestor. Then, you need an organism C, which is the youngest form of the species. Then, you need the transitional life form B, which shows some kind of biochemical structure or system that is in transition from A to C.
Two special features of a bat make them a very unique mammal: (1) Echolocation, and (2) Flight. The first hypothesis offered by Darwinists is that these two functions probably did not evolve simultaneously, but one developed before the other did. Therefore, the related hypothesis would be that when an ancestor of the bat, or a more primitive form of a bat is discovered in the fossil record, chances are good that the specimen will have only one feature, either (1) echolocation or (2) flight, but not both.
Onychonycteris had short, broad wings with claws, very reminiscent of dinosaur birds such as archeopteryx, and also another example of convergent evolution, which is more an argument for design than it is evolution. Onychonycteris had long hind legs with a broad tail.
Two years ago, “the most primitive bat known” was reported in Nature. It was not primitive in its wings and body, but “the morphology of the ear region suggests that it could not echolocate, making it a possible intermediate link between bats and their non-flying, non-echolocating mammalian ancestors”. At the time, the find was suggested to settle the question as to which came first: flight or echolocation? The answer was a definite flight first.
But, what is most important that Darwinists point out is that Onychonycteris finneyi is the strongest evidence so far in the debate on whether bats developed echolocation before or after they evolved the ability to fly. O. finneyi had well-developed wings, and could clearly fly, but lacked the enlarged cochlea of all extant echolocating bats, closer resembling the old world fruit bats which do not echolocate. This indicates that early bats could fly before they could echolocate It is unknown whether Onychonycteris had the large eyes of most nocturnal animals as specimens with intact eye sockets have yet to be found.
“The problem of understanding bat evolution dates back at least to Charles Darwin, who in The Origin of Species enumerated a list of difficulties he saw with the theory of evolution by natural selection. The example often discussed is the origin of the eye. But Darwin also mentioned the vexed issue of how bats had arisen from terrestrial ancestors.” [http://www.nature.com/nature/journal/v451/n7180/full/451774a.html]
This assessment of the fossil must now be reappraised. New work on modern-day bats has revealed another mechanism of echolocation. One of the authors described the work thus:
“We borrowed 35 specimens from the Royal Ontario Museum in Toronto and performed micro-computed tomography on them. This imaging technique allowed us to see the fine details of the bats’ ear and throat regions: the larynges, stylohyals and tympanic bones. Previous work had relied on dissecting these bones, a challenge in animals as small as bats. We found that the fusion or connection of two bone structures – the stylohyal bone in a bat’s throat and the tympanic bone in the ear region of its skull – was a feature of all laryngeally echolocating bat species we studied.”
This finding is new and unexpected. It means that previous conclusions need to be reappraised. This is exactly what is happening with the “most primitive fossil bat”.
“The relatively small cochleae and lack of paddle-like expansions on the cranial tips of the stylohyal bones have been interpreted as evidence that O. finneyi lacked laryngeal echolocation, which supports the hypothesis that flight evolved before echolocation. However, we find that articulation between the stylohyal and tympanic bones is a better predictor of laryngeal echolocation ability than the shape of the stylohyal bone, at least among extant bats. If the stylohyal bones articulated with the tympanic bones in O. finneyi, then we propose that this species had the capacity for laryngeal echolocation. Our results thus reopen basic questions about the timing of the appearance of echolocation and flight in the evolution of bats.”
There are several lessons to be learned here – and one of these is to always be prepared to hold judgment on the word “primitive” – even if it is said to be the “most primitive”!
A bony connection signals laryngeal echolocation in bats
Nina Veselka, David D. McErlain, David W. Holdsworth, Judith L. Eger, Rethy K. Chhem, Matthew J. Mason, Kirsty L. Brain, Paul A. Faure & M. Brock Fenton
Nature 463, 939-942 (18 February 2010) | doi:10.1038/nature08737
Echolocation is usually associated with bats. Many echolocating bats produce signals in the larynx, but a few species produce tongue clicks. Here, studies show that in all bats that use larynx-generated clicks, the stylohyal bone is connected to the tympanic bone. Study of the stylohyal and tympanic bones of a primitive fossil bat indicates that this species may have been able to echolocate, despite previous evidence to the contrary, raising the question of when and how echolocation evolved in bats.
The conclusion is that there is no evidence to determine that bats ever lacked echolocation. Onychonycteris is not a persuasive transitional life form by any stretch of the imagination.
Adult flatfish have asymmetrical skulls, with both their two eyes located on just one side of the head [http://www.lessonplanspage.com/graphics/SciencePEArtLAMDFlatfishMovementActivityGraphic.JPG]
One eye actually “migrates” from one side of the head to the other, it’s as if the skull is rotated 90 degrees to one side. There is no third eye on the opposite side of a flatfish head.
Enter Amphistium and Heteronectes. These are two fossil specimens that also had asymmetrical skulls and eyes on the same side of the head. Each of these species is said by Darwinists to be an intermediate life form.
Amphistium and Heteronectes were two genera of fish representing the transition toward modern flatfishes, which in their adult form have two eyes on the same side of the head. Flatfish when hatched are symmetrical, but during their growth to maturity one of the eyes migrates to the other side of the head.
Typical modern flatfish lie (in wait for prey) on one side, and have their two eyes on the same side of their head (rather than having them symmetrically located as is typical for vertebrates, which would have one eye uselessly facing downward). The fossils of Amphistium and Heteronectes are alleged to show a transitional state, with one eye in an intermediate position, moved near the top of the head. It is claimed that this is intermediate between the typical location for eyes in vertebrates symmetrically placed in the head, and the typical location for eyes in flatfishes on the same side of the head. There are several fossils of Amphistium known from different locations, so it is not just an isolated malformed fish. [http://rationalwiki.org/wiki/Amphistium_and_Heteronectes].
Here’s another look at the eye migration of what is also called the Picasso fish, http://littlegreenfootballs.com/article/30620_Evolution_in_Action-_The_Picasso_Fish.
I am impressed with this adaptation. We certainly do see here a transitional life form showing the intermediate stages of an adaptation. And, that’s the key word here. No ID proponent or creationist that I am aware of refutes microevolution. All these organisms presented here are basic variations of the same suborder Perciformes. There was no macroevolution taking place here. There is no increase in information. All we have is an eye that migrates from one side of the skull to the other. I admit that this is a very impressive adaptation, but that’s all this is, it’s an adaptation.
Yes, we do witness the intermediate developmental stages of an adaptation taking place. But, an ID proponent or creationist will concede to you as a given that variations and adaptations take place.
Manatees and dugongs are fully aquatic mammals with flippers and no hind limbs. Biologists and paleontologists consider Sirenians to be linked genetically to elephants. As such, an hypothesis is offered that primitive Sirenian fossils will shoe hind limbs. So, we are back to the same situation we encountered already above with snakes.
Enter Pezosiren [http://www.geocities.co.jp/NatureLand/5218/pezosiren.JPG]. The Pezosiren is the most primitive Sirenian specimen found yet to date in the fossil record. It was fully capable of walking on land, but spent much of its time in water. It is suggested to be a perfect example of a transitional form between a land mammal and a sea mammal [http://en.wikipedia.org/wiki/Pezosiren]. It had the skull and basic body shared by most modern sirenians, like manatees and dugongs, but also had four normal limbs with well-developed feet and hands, still adapted for walking on land.
The Pezosiren portelli possessed a skeleton and strong legs capable of supporting its bodyweight out of water. In an article published in Nature [http://www.nature.com/index.html?file=%2Fnature%2Fjournal%2Fv413%2Fn6856%2Ffull%2F413625a0_fs.html&filetype&_UserReference=C0A804F54650B91AAAEDAA76B66C3EC2303F], we find are described an animal that “was fully capable of locomotion on land, with four well-developed legs, a multivertebral sacrum, and a strong sacroiliac articulation that could support the weight of the body out of water as in land mammals.” As would be expected, Pezosiren portelli was FULLY DEVELOPED with biochemical structures in any kind of intermediate state of development.
Anatomically, the Pezosiren portelli was almost indistinguishable from land mammals. The apparent reason for Domning’s assertion in the Nature magazine article is that this was an animal in the process of evolving into a sea mammal was the relatively set back location of its nostrils and that it lacked paranasal sinuses. The cause for Domning’s excitement because of its setback nostrils is the fact that sea mammals like whales and dolphins have their nostrils located on the crown of the head. Evolutionists presume that land mammals evolved gradually into sea mammals and in the process of this development, the nostrils located at the front part of the scull became more and more setback towards the crown. This supposition however has no bearings on the manatees, because their nostrils, as seen in the picture below, are located at the front. For this reason their nostrils do not open upwards and it would be inconsistent to consider them within the hypothesis put forward in relation to the change of the nostrils’ location.
Another inconsistency in the evolution scenario of the manatees’ nostrils reveals itself in the fact that manatees sleep underwater and keep their nostrils shut while asleep. Nasal valves keep the air trapped inside and the water out during their sleep. The question that needs answering by evolutionists is how such functional valves, essential for the prevention of drowning during sleep, could have evolved by blind and random mutations. Despite the lack of a rational explanation, evolutionists still stubbornly believe that it nevertheless happened.
In reality such preventive systems are the product of conscious design like, for instance, the valves controlling the water intake in mini submarines. The ‘valves’ located inside the nostrils are from a survival point of view exactly at the right place and in the right form to seal the opening. It is obvious that this functionality in the manatees, which are in and out the water, is by design. Similar features can be observed in the valves of submarines, obviously designed and built by engineers. To claim that these were placed there accidentally would be irrational just like it is irrational to suggest that the ‘valves’ in the manatees nostrils developed there by blind coincidental mutations.
In reality, the Pezosiren portelli is nothing other than an extinct land mammal. Its ability to sustain itself in water does not suffice to support the claim that it is the ancestor of the manatee, or even a transition from a sea mammal to a land mammal of any kind.
The hippopotamus of today is a creature spending much of its time in the water, but this situation does not mean that they, some time in the future, will have their legs transformed into flippers and become sea mammals living in the sea. It is possible to detect similarities between a car and a bicycle; they both have wheels but it would be just ridiculous to claim that cars gradually loose some of its wheels and turn into bicycles. Likewise it is ridiculous to propose that the Pizosiren portelli evolved gradually into manatees without showing any of the supposed evolution mechanisms taking place, for instance the mutations responsible for the development of the flippers.